AP Biology Practice Test 37

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Question 10 questions

Time 14 minutes

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1. In the process of generating ATP, hydrogen ions (H+, or protons) are transported across the inner mitochondrial membrane and the thylakoid membrane by a proton pump (an ATPase). You would expect to find similar proton pumps in the plasma membranes of

Questions 2-4 refer to the following information.

The pink mold Neurospora obtains all of its nutritional requirements when it grows on bread. In the laboratory, a minimal culture medium can be prepared that also allows Neurospora to grow. When wild-type Neurospora is exposed to x-rays, however, the resulting induced mutants can only grow on media that have been supplemented with additional nutrients. Various nutritional supplements to the minimal medium for each of four mutants are shown in the following table. Each of the mutants possesses a single mutation that inactivates a single biochemical conversion. Growth occurs when any one of the supplements indicated by a plus sign is added to the minimum culture medium.

Supplements to Minimal Medium
Minimal MediumOrnithineCitrullineArgininosuccinateArginine
Mutant I++++
Mutant II+++
Mutant III++
Mutant IV+

2. Which of the following describes the metabolic pathway for the synthesis of arginine?

3. Mutant II will grow if citrulline, argininosuccinate, or arginine is added to the minimal medium. If a small amount of citrulline is added to allow growth to begin, what product is expected to have accumulated after all the added citrulline is used up?

4. Which of the following mutant cultures can grow if ornithine, citrulline, and argininosuccinate are all added to the minimal medium?

Questions 5-8 refer to the following information.

A plant produces fruits that are either red or white and that have either a smooth or a spiny surface. Table I shows the phenotypes of the F1 offspring that result from crossing true-breeding parents with these traits.

Three groups of students then used computer simulations to predict the numbers of each phenotype produced when F1 progeny were test crossed to individuals homozygous recessive for both traits. The results of the computer simulations are shown in Table II.

Cross of True-Breeding Parents

PF 1
Red × WhiteAll Red
Smooth × SpinyAll Smooth
Red and Smooth × White and SpinyAll Red and Smooth

Test Cross of F1

Phenotypes Produced from Test Cross of F 1Number of Offspring Generated
Simulation 1Simulation 2Simulation 3
Red and Smooth394155272
Red and Spiny4050124
White and Smooth4150116
White and Spiny386145288

5. The results of the cross of true-breeding parents in Table I indicate that no F1 individuals express the white or spiny traits. How can this best be explained?

6. The results shown in Table II for each of the computer simulations are different, presumably because the students made different assumptions about how the traits of color and texture are inherited. Which of the following best explains the results generated by simulation 1?

7. In simulation 2, no individuals were generated with red and spiny or white and smooth fruits. Which of the following best explains these results?

8. Although all four phenotypes are generated by simulation 3, the numbers are different than those generated by simulation 1. How can this best be explained?

9. The following graph plots the size of the stomatal aperture as a function of time of day for a typical plant under various environmental conditions. Three environments are investigated: normal conditions, very dry soil, and an experimentally induced low CO2 environment.

Which of the following is best supported by the data presented in the graph?


An iodine solution (IKI or Lugol's solution) turns from yellow-brown to blue when it reacts with starch, but not when it reacts with glucose. A bag made from a selectively permeable material and containing iodine solution is placed into a beaker containing a solution of glucose and starch. Using only this information, which of the following can be correctly concluded if the solution in the beaker turns blue but the contents of the bag remain unchanged in color?